2,807 research outputs found
Analyzing Europe’s Biggest Offshore Wind Farms: A Data Set with 40 Years of Hourly Wind Speeds and Electricity Production
We provide an open, available, and ready-to-use data set covering 40 years of hourly wind speeds and synthetic hourly production signals for the 29 biggest offshore wind farms in Europe. It enables researchers and industry experts to include realistic offshore time series into their analyses. In particular, we provide data from 1980 to 2019 for wind farms already in operation and those that will be in operation by 2024. We document in detail how the data set was generated from publicly available sources and provide manually collected details on the wind farms, such as the turbine power curves. Correspondingly, the users can easily keep the data set up to date and add further wind farm locations as needed. We give a descriptive analysis of the data and its correlation structure and find a relatively high volatility and intermittency for single locations, with balancing effects across wind farms
Borneo stalagmite evidence of significantly reduced El Niño-Southern Oscillation variability at 4.1 kyBP
The timing and geographic extent of a potential “4.2 ky event” remain highly contested. Here we present records of ENSO variability at 3.8 kyBP and 4.1 kyBP derived from a Borneo stalagmite, which suggest a significant change in ENSO properties between these time intervals. The Borneo records show evidence of significantly reduced ENSO activity at 4.1 kyBP, relative to other measured windows within the Holocene. This reduced ENSO activity coincides with a period of drier conditions and enhanced dust events in the Middle East that took place ∼4.0–4.3 kyBP. The Borneo records show evidence of enhanced ENSO activity at 3.8 kyBP. Various hydroclimate changes attributed to the “4.2 ky event” in many regions may thus be reflecting a shift from reduced to enhanced El Niño activity that occurred between 3.8 kyBP to 4.0 kyBP
Four distinct trajectories of tau deposition identified in Alzheimer's disease
Alzheimer’s disease (AD) is characterized by the spread of tau pathology throughout the cerebral cortex. This spreading pattern was thought to be fairly consistent across individuals, although recent work has demonstrated substantial variability in the population with AD. Using tau-positron emission tomography scans from 1,612 individuals, we identified 4 distinct spatiotemporal trajectories of tau pathology, ranging in prevalence from 18 to 33%. We replicated previously described limbic-predominant and medial temporal lobe-sparing patterns, while also discovering posterior and lateral temporal patterns resembling atypical clinical variants of AD. These ‘subtypes’ were stable during longitudinal follow-up and were replicated in a separate sample using a different radiotracer. The subtypes presented with distinct demographic and cognitive profiles and differing longitudinal outcomes. Additionally, network diffusion models implied that pathology originates and spreads through distinct corticolimbic networks in the different subtypes. Together, our results suggest that variation in tau pathology is common and systematic, perhaps warranting a re-examination of the notion of ‘typical AD’ and a revisiting of tau pathological staging
Distribution of cholinergic nerve terminals in the aged human brain measured with [18F]FEOBV PET and its correlation with histological data
Introduction: [18F]fluoroetoxybenzovesamicol ([18F]FEOBV) is a positron emission topography (PET) tracer for the vesicular acetylcholine transporter (VAChT), a protein located predominantly in synaptic vesicles in cholinergic nerve terminals. We aimed to use [18F]FEOBV PET to study the cholinergic topography of the healthy human brain. Materials and methods: [18F]FEOBV PET brain data volumes of healthy elderly humans were normalized to standard space and intensity-normalized to the white matter. Stereotactic atlases of regions of interest were superimposed to describe and quantify tracer distribution. The spatial distribution of [18F]FEOBV PET uptake was compared with histological and gene expression data. Results: Twenty participants of both sexes and a mean age of 73.9 ± 6.0 years, age-range [64; 86], were recruited. Highest tracer binding was present in the striatum, some thalamic nuclei, and the basal forebrain. Intermediate binding was found in most nuclei of the brainstem, thalamus, and hypothalamus; the vermis and flocculonodular lobe; and the hippocampus, amygdala, insula, cingulate, olfactory cortex, and Heschl's gyrus. Lowest binding was present in most areas of the cerebral cortex, and in the cerebellar nuclei and hemispheres. The spatial distribution of tracer correlated with immunohistochemical post-mortem data, as well as with regional expression levels of SLC18A3, the VAChT coding gene. Discussion: Our in vivo findings confirm the regional cholinergic distribution in specific brain structures as described post-mortem. A positive spatial correlation between tracer distribution and regional gene expression levels further corroborates [18F]FEOBV PET as a validated tool for in vivo cholinergic imaging. The study represents an advancement in the continued efforts to delineate the spatial topography of the human cholinergic system in vivo
Measurement of inclusive D*+- and associated dijet cross sections in photoproduction at HERA
Inclusive photoproduction of D*+- mesons has been measured for photon-proton
centre-of-mass energies in the range 130 < W < 280 GeV and a photon virtuality
Q^2 < 1 GeV^2. The data sample used corresponds to an integrated luminosity of
37 pb^-1. Total and differential cross sections as functions of the D*
transverse momentum and pseudorapidity are presented in restricted kinematical
regions and the data are compared with next-to-leading order (NLO) perturbative
QCD calculations using the "massive charm" and "massless charm" schemes. The
measured cross sections are generally above the NLO calculations, in particular
in the forward (proton) direction. The large data sample also allows the study
of dijet production associated with charm. A significant resolved as well as a
direct photon component contribute to the cross section. Leading order QCD
Monte Carlo calculations indicate that the resolved contribution arises from a
significant charm component in the photon. A massive charm NLO parton level
calculation yields lower cross sections compared to the measured results in a
kinematic region where the resolved photon contribution is significant.Comment: 32 pages including 6 figure
Measurement of Jet Shapes in Photoproduction at HERA
The shape of jets produced in quasi-real photon-proton collisions at
centre-of-mass energies in the range GeV has been measured using the
hadronic energy flow. The measurement was done with the ZEUS detector at HERA.
Jets are identified using a cone algorithm in the plane with a
cone radius of one unit. Measured jet shapes both in inclusive jet and dijet
production with transverse energies GeV are presented. The jet
shape broadens as the jet pseudorapidity () increases and narrows
as increases. In dijet photoproduction, the jet shapes have been
measured separately for samples dominated by resolved and by direct processes.
Leading-logarithm parton-shower Monte Carlo calculations of resolved and direct
processes describe well the measured jet shapes except for the inclusive
production of jets with high and low . The observed
broadening of the jet shape as increases is consistent with the
predicted increase in the fraction of final state gluon jets.Comment: 29 pages including 9 figure
Plastisol Foaming Process. Decomposition of the Foaming Agent, Polymer Behavior in the Corresponding Temperature Range and Resulting Foam Properties
The decomposition of azodicarbonamide, used as foaming agent in PVC - plasticizer (1/1) plastisols was studied by DSC. Nineteen different plasticizers, all belonging to the ester family, two being polymeric (polyadipates), were compared. The temperature of maximum decomposition rate (in anisothermal regime at 5 K min-1 scanning rate), ranges between 434 and 452 K. The heat of decomposition ranges between 8.7 and 12.5 J g -1. Some trends of variation of these parameters appear significant and are discussed in terms of solvent (matrix) and viscosity effects on the decomposition reactions. The shear modulus at 1 Hz frequency was determined at the temperature of maximum rate of foaming agent decomposition, and differs significantly from a sample to another. The foam density was determined at ambient temperature and the volume fraction of bubbles was used as criterion to judge the efficiency of the foaming process. The results reveal the existence of an optimal shear modulus of the order of 2 kPa that corresponds roughly to plasticizer molar masses of the order of 450 ± 50 g mol-1. Heavier plasticizers, especially polymeric ones are too difficult to deform. Lighter plasticizers such as diethyl phthalate (DEP) deform too easily and presumably facilitate bubble collapse
D* Production in Deep Inelastic Scattering at HERA
This paper presents measurements of D^{*\pm} production in deep inelastic
scattering from collisions between 27.5 GeV positrons and 820 GeV protons. The
data have been taken with the ZEUS detector at HERA. The decay channel
(+ c.c.) has been used in the study. The
cross section for inclusive D^{*\pm} production with
and is 5.3 \pms 1.0 \pms 0.8 nb in the kinematic region
{ GeV and }. Differential cross
sections as functions of p_T(D^{*\pm}), and are
compared with next-to-leading order QCD calculations based on the photon-gluon
fusion production mechanism. After an extrapolation of the cross section to the
full kinematic region in p_T(D^{*\pm}) and (D^{*\pm}), the charm
contribution to the proton structure function is
determined for Bjorken between 2 10 and 5 10.Comment: 17 pages including 4 figure
- …